RESUMEN
This study was to evaluate the mechanistic effect of protein to help better interpret the permeability results for compounds with low mass balance in Caco-2 permeability assay. The absorptive or bi-directional permeability of lipophilic compounds with mass balance were measured across Caco-2 cell monolayers as well as the empty transport devices with or without protein (4% bovine serum albumin, BSA) added to the receiver side. The results from empty transport device study indicated that the filter membrane is a permeability barrier for the low mass balance compounds and protein increases permeability by improving the compound diffusivity through the filter membrane. Caco-2 permeability measured with protein provided better absorption projection. Assuming the amount of compound associated with cells as transported did not correlate with absorption. For efflux substrate identification using Caco-2 bi-directional permeability assay, protein at the receiver side had no significant effect on the conclusion regarding the tested compounds as efflux substrate but increased the permeability measurement from both transport directions. In conclusions, Caco-2 permeability results measured using protein-containing buffer at the receiver side for low mass balance compound seems to provide better correlation with in vivo absorption. The fact that protein at receiver side has minimal effect on efflux substrate identification provides scientific basis for further specific transporter characterization (such as P-gp or BCRP) using specific inhibitors, in which same concentration of inhibitor is used in both sides of the Caco-2 cell system and protein for optimal permeability assessment has to be avoided.
Asunto(s)
Bioensayo , Absorción Intestinal , Mucosa Intestinal/metabolismo , Preparaciones Farmacéuticas/metabolismo , Albúmina Sérica Bovina/metabolismo , Animales , Bioensayo/métodos , Transporte Biológico , Tampones (Química) , Células CACO-2 , Bovinos , Difusión , Humanos , Estructura Molecular , Peso Molecular , Permeabilidad , Preparaciones Farmacéuticas/química , Reproducibilidad de los ResultadosRESUMEN
The permeability of six peptidic hepatitis C virus (HCV) protease inhibitors, with molecular weights ranging from 500 to 780, was examined in the Caco-2 cell system. All six compounds permeated the cells transcellularly; paracellular permeability, evaluated in the Caco-2 cell system by reducing the calcium concentration in the media to increase the pore size of the tight junctions, most likely contributes only minimally to the oral absorption of the compounds. All six compounds were shown to be efflux substrates displaying concentration-dependent saturation of efflux. The efflux could be blocked by cyclosporine A, a specific P-glycoprotein (P-gp) inhibitor, suggesting that P-gp may be the responsible transporter. Oral absorption in rats was calculated using in vivo oral bioavailability and hepatic extraction ratios. Human oral absorption was projected to be similar to that of rats, as reported previously by comparing rat and human absorption values for 23 marketed drugs. Upon comparison of human oral absorption predicted by Caco-2 permeability and by rat pharmacokinetics, we show a better correlation with Caco-2 permeability obtained at higher compound concentrations, where efflux is saturated, than at lower concentrations. The higher concentrations are likely reflecting the lumen concentrations after in vivo oral dosing. The results presented in this study demonstrate that, when tested at relevant compound concentrations, Caco-2 permeability is useful for predicting the oral absorption of peptidic compounds.
Asunto(s)
Hepacivirus , Péptidos/farmacocinética , Inhibidores de Proteasas/farmacocinética , Miembro 1 de la Subfamilia B de Casetes de Unión a ATP , Absorción , Administración Oral , Animales , Disponibilidad Biológica , Células CACO-2 , Permeabilidad de la Membrana Celular , Humanos , Hígado/metabolismo , Permeabilidad , Ratas , Uniones Estrechas/metabolismoRESUMEN
A human pregnane X receptor (PXR) reporter-gene assay was established and validated using 19 therapeutic agents known to be clinical CYP3A4 inducers, 5 clinical non-inducers, and 6 known inducers in human hepatocytes. The extent of CYP3A4 induction (measured as RIF ratio in comparison to rifampicin) and EC50 was obtained from the dose-response curve. All of the clinical inducers (19/19) and human hepatocyte inducers (6/6) showed positive responses in the PXR assay. One out of five clinical non-inducers, pioglitazone, also showed a positive response. An additional series of 18 commonly used drugs with no reports of clinical induction was also evaluated as putative negative controls. Sixteen of these were negative (89%), whereas two of these, flutamide and haloperidol showed 16-fold (RIF ratio 0.79) and 10-fold (RIF ratio 0.48) maximal induction, respectively in the reporter-gene system. Flutamide and haloperidol were further demonstrated to cause CYP3A4 induction in human cryopreserved hepatocytes based on testosterone 6beta-hydroxylation activity. The induction potential index calculated based on the maximum RIF ratio, EC50, and in vivo maximum plasma concentration was used to predict the likelihood of CYP3A4 induction in humans. When the induction potential index is greater than 0.08, the compound is likely to cause induction in humans. A high-throughput screening strategy was developed based on the validation results at 1microM and 10microM for the same set of drugs. A RIF ratio of 0.4 was set as more practical screening cut-off to minimize the possibility of generating false positives. Thus, a tiered approach was implemented to use the human PXR reporter-gene assay from early lead optimization to late lead characterization in drug discovery.
Asunto(s)
Citocromo P-450 CYP3A/genética , Evaluación Preclínica de Medicamentos/métodos , Inducción Enzimática/efectos de los fármacos , Genes Reporteros , Hepatocitos/efectos de los fármacos , Receptores de Esteroides/metabolismo , Secuencia de Bases , Línea Celular , Cartilla de ADN , Hepatocitos/enzimología , Humanos , Luciferasas de Luciérnaga/genética , Reacción en Cadena de la Polimerasa , Receptor X de PregnanoRESUMEN
Parallel artificial membrane permeability assay (PAMPA) and Caco-2 cells have been frequently used for the evaluation of in vitro permeability of new chemical entities. In this study we evaluated the correlation between permeability, assessed by both methods, and the cellular potency of 34 novel hepatitis C virus (HCV) protease inhibitors. Two types of assays were used to determine the potency of HCV protease inhibitors: a cell-free assay that evaluates the intrinsic affinity (K(i)) between the protease and the inhibitor and a cell-based replicon assay that determines the inhibitors' IC90. When the K(i)/IC90 ratios were compared with the PAMPA permeability and the Caco-2 permeability by linear regression analysis, a reasonable correlation was found between the K(i)/IC90 ratio and PAMPA permeability (r2=0.76) but not with Caco-2 permeability (r2=0.29). Correlations were also assessed between K(i)/IC90 ratios and the following physico-chemical properties: logP (r2=0.41), logD (r2=0.58), clogP (r2=0.13), and mlogP (r2=0.30). These results suggest that passive permeability may play a role in the uptake and cellular activity of these HCV protease inhibitors, and that PAMPA was more predictive of cellular activity than physico-chemical properties or Caco-2 permeability.
Asunto(s)
Permeabilidad de la Membrana Celular , Membranas Artificiales , Inhibidores de Proteasas/metabolismo , Células CACO-2 , Difusión , Hepacivirus , Humanos , Proteínas Recombinantes/metabolismo , Proteínas no Estructurales Virales/antagonistas & inhibidoresRESUMEN
Permeability estimates using Caco-2 cells do not accurately predict the absorption of hydrophilic drugs that are primarily absorbed via the paracellular pathway. The objective of this study was to investigate whether modulation of tight junctions would help differentiation of paracellularly absorbed compounds. Tight junctions in Caco-2 cell monolayers were manipulated using calcium depletion approaches to decrease the transepithelial electrical resistance (TEER) of the monolayers, and permeability of hydrophilic compounds were measured under these conditions. Permeability of these compounds were also measured in Calu-3 cells, which have tighter junctions than Caco-2 cells. Calcium depletion loosened the tight junctions of Caco-2 cells to varying levels as measured by the decrease in TEER values of the monolayers. While the absolute permeability of all the model compounds increased as the tight junctions were loosened, the ratios of their permeability relative to mannitol permeability were similar. The permeability of these compounds in the tighter Calu-3 cells were also found to be similar to each other. Altering the tight junctions of Caco-2 cells to obtain leakier cell monolayers, or using a cell line with tighter junctions like Calu-3 cells, did not improve differentiation between well absorbed and poorly absorbed hydrophilic drugs. Mere manipulation of the tight junctions to increase or decrease transepithelial electrical resistance does not appear to be a viable approach to predict human absorption for hydrophilic compounds that are primarily absorbed via the paracellular pathway.
Asunto(s)
Permeabilidad de la Membrana Celular , Células Epiteliales/metabolismo , Mucosa Bucal/metabolismo , Preparaciones Farmacéuticas/metabolismo , Uniones Estrechas/metabolismo , Absorción , Células CACO-2 , Calcio/metabolismo , Células Epiteliales/fisiología , Humanos , Preparaciones Farmacéuticas/química , Uniones Estrechas/fisiologíaRESUMEN
This paper describes the development and qualification of a fast, sensitive and specific ultra-performance liquid chromatography/tandem mass spectrometric (UPLC/MS/MS) method for the determination of diastereomers of SCH 503034 in monkey plasma. The analytical method involves direct protein precipitation with a mixture of methanol/acetonitrile (10/90) containing an internal standard, followed by separation of the stereoisomers on an Acquity UPLC C(18) column and detected by selected reaction monitoring (SRM) in positive ionization mode using atmospheric pressure chemical ionization (APCI). The effects of ion-pairing agents on separation and ionization efficiency were investigated. The two diastereomers were well separated (R=1.3) with a runtime of 5 min under an isocratic condition. The method was qualified. The linear concentration range was 1-2500 ng/ml for the both stereoisomers. Inter-assay mean bias and relative standard deviation (R.S.D.) were in the range of -1.2% to 3.6% and 2.8-10%, respectively. Intra-assay mean bias and R.S.D. were in the range of -1.3% to 5.5% and 2.3-7.8%, respectively. Recoveries of the stereoisomers at concentration levels of 2.5, 50 and 1000 ng/ml were 87.2-90.0%, 89.1-90.4% and 92.3-94.3%, respectively. The LLOQ for this assay was 1 ng/ml. No matrix interferences were observed in six different sources of blank monkey plasma.
Asunto(s)
Cromatografía Liquida/métodos , Prolina/análogos & derivados , Espectrometría de Masas en Tándem/métodos , Animales , Macaca fascicularis , Masculino , Prolina/sangre , Prolina/química , Estándares de Referencia , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , EstereoisomerismoRESUMEN
Recent studies have suggested that both constitutive androstane receptor (CAR) and pregnane X-receptor (PXR) are involved in the induction of rat liver microsomal cytochrome P-450 (CYP) 2B and 3A through a mechanism called cross-talk. In this study we intend to determine if a PXR-reporter gene assay could be used for the prediction of CYP3A and/or CYP2B induction in rats. The induction of rat CYP2B and CYP3A by nineteen structurally diverse compounds was evaluated by using rat precision-cut liver slices and a rat PXR reporter-gene system. Induction of CYP2B and CYP3A mRNAs in rat liver slices was quantified by real-time polymerase chain reaction. Rat PXR activation was measured by induction of luciferase activity in rat PXR reporter-gene system. Linear regression analysis of the fold of induction of mRNA in liver slices and the fold of luciferase activity in rat PXR reporter-gene system shows that a reasonable correlation (r2 = 0.6) exists between the CYP3A induction and the rat PXR activation. A much lower correlation was observed between CYP2B induction and the rat PXR activation (r2 = 0.1). The results from this study suggest that the PXR may play a major role in the induction of rat CYP3A, but not CYP2B. Therefore, the PXR-reporter gene assay may be useful in a high-throughput screening to predict CYP3A induction in rats.
Asunto(s)
Hidrocarburo de Aril Hidroxilasas/metabolismo , Bioensayo , Hígado/metabolismo , Oxidorreductasas N-Desmetilantes/metabolismo , Receptores Citoplasmáticos y Nucleares/genética , Receptores de Esteroides/genética , Animales , Hidrocarburo de Aril Hidroxilasas/efectos de los fármacos , Hidrocarburo de Aril Hidroxilasas/genética , Citocromo P-450 CYP2B1/efectos de los fármacos , Citocromo P-450 CYP2B1/genética , Citocromo P-450 CYP2B1/metabolismo , Citocromo P-450 CYP3A , Evaluación Preclínica de Medicamentos/métodos , Activación Enzimática/efectos de los fármacos , Genes Reporteros , Técnicas In Vitro , Hígado/efectos de los fármacos , Luciferasas/efectos de los fármacos , Luciferasas/genética , Luciferasas/metabolismo , Masculino , Oxidorreductasas N-Desmetilantes/efectos de los fármacos , Oxidorreductasas N-Desmetilantes/genética , Receptor X de Pregnano , ARN Mensajero/efectos de los fármacos , ARN Mensajero/metabolismo , Ratas , Ratas Sprague-Dawley , Receptores Citoplasmáticos y Nucleares/efectos de los fármacos , Receptores Citoplasmáticos y Nucleares/metabolismo , Receptores de Esteroides/efectos de los fármacos , Receptores de Esteroides/metabolismoRESUMEN
INTRODUCTION: In drug development, new chemical entities that cause cytochrome P450 induction are considered to be undesirable since P450 induction is linked to tumor formation and may compromise the evaluation of drug safety when autoinduction results in poor drug exposure. METHODS: We evaluated the use of the precision-cut liver slice as a model for measuring induction of cytochrome P450 in rats. Quantitative real-time reverse-transcription polymerase chain reaction was used to analyze the induction of selected forms of cytochrome P450 at the mRNA level. Firstly, the system was validated against known inducers of CYP2B and 3A. Subsequently, 26 proprietary compounds were tested in rat liver slices and rats in vivo for CYP2B and 3A induction. RESULTS: Exposure of liver slices to the known CYP2B inducers phenobarbital, benzoyl-pyridine, cabarmazepine, metyrapone, RU486 and dexamethasone caused elevation of CYP2B1/2 expression 10- to 40-fold compared to the control values. The CYP3A inducers PCN, dexamethasone, nicardipine, nifedipine, clotrimazole and RU486 induced a 4- to 50-fold expression of CYP3A14. For 26 proprietary compounds, a correlation with an R(2) value of 0.74 was established between the induction of CYP2B expression in liver slices and that in rats in vivo. When liver slice results were used to predict the induction of CYP2B in rats in vivo, the success rate was 91%. The induction of CYP3A in rats in vivo was analyzed by Western blot, then quantified by densitometry. There was a good correlation between CYP3A induction in liver slices and induction in vivo as assessed by Western blot, with an 86% positive prediction rate. DISCUSSION: The use of liver slices in combination with TaqMan technology provides a good model for predicting CYP induction in the rat. This method is useful for identifying compounds with CYP2B and 3A induction liability in the early phase of drug discovery.
Asunto(s)
Hidrocarburo de Aril Hidroxilasas/metabolismo , Citocromo P-450 CYP2B1/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/métodos , Algoritmos , Animales , Hidrocarburo de Aril Hidroxilasas/genética , Carbamazepina/farmacología , Citocromo P-450 CYP2B1/genética , Citocromo P-450 CYP3A , Cartilla de ADN/genética , Dexametasona/farmacología , Relación Dosis-Respuesta a Droga , Regulación Enzimológica de la Expresión Génica/efectos de los fármacos , Hígado/efectos de los fármacos , Hígado/metabolismo , Masculino , Metirapona/farmacología , Microsomas Hepáticos/efectos de los fármacos , Microsomas Hepáticos/metabolismo , Mifepristona/farmacología , ARN Mensajero/genética , ARN Mensajero/metabolismo , Ratas , Ratas Sprague-Dawley , Esteroide Hidroxilasas/genética , Esteroide Hidroxilasas/metabolismoRESUMEN
BMS-262084 is a potent and selective beta-lactam tryptase inhibitor with therapeutic potential for treating asthma. The oral bioavailability of BMS-262084 was low in rats (4% at a dose of 0.5 mg/kg) due to poor absorption. BMS-262084 was excreted mainly unchanged in the urine, suggesting minimal metabolism in rats. The objective of this study was to investigate the mechanisms of oral absorption of BMS-262084 in rats. Modulation of intestinal tight junctions, binding to trypsin, and involvement of the intestinal dipeptide transport system and P-glycoprotein (P-gp) in the absorption of BMS-262084 were examined. Coadministration of BMS-262084 with SQ-29852, a substrate of the intestinal dipeptide transport system, did not change the oral absorption of BMS-262084. An increase in the dose of BMS-262084 from 0.5 to 50 mg/kg resulted in a 3.7-fold increase in its oral absorption. Inulin absorption was enhanced upon coadministration with BMS-262084, suggesting the opening of tight junctions in the intestinal epithelium. Coadministration of aprotinin, a trypsin inhibitor, increased the oral absorption of BMS-262084 several fold. In vitro, using Caco-2 cells, BMS-262084 appeared to be a P-gp substrate, with an efflux ratio of 14. These results suggest that absorption of BMS-262084 is mediated by several concurrent mechanisms. At higher doses of BMS-262084, increased absorption may be primarily due to opening of tight junctions in the intestinal epithelium and consequent absorption via the paracellular pathway, while at lower doses, binding to trypsin may contribute to limiting its absorption. P-gp efflux may also play a role in influencing the absorption of BMS-262084. The intestinal dipeptide transporter system does not appear to be involved in the absorption of BMS-262084.
Asunto(s)
Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/metabolismo , Azetidinas/farmacocinética , Piperazinas/farmacocinética , Inhibidores de Serina Proteinasa/farmacocinética , Tripsina/metabolismo , Administración Oral , Animales , Azetidinas/administración & dosificación , Azetidinas/farmacología , Disponibilidad Biológica , Células CACO-2 , Dipéptidos/metabolismo , Relación Dosis-Respuesta a Droga , Humanos , Hipoglucemiantes , Inyecciones Intraarteriales , Insulina , Absorción Intestinal , Piperazinas/administración & dosificación , Piperazinas/farmacología , Unión Proteica , Ratas , Ratas Sprague-Dawley , Serina Endopeptidasas/metabolismo , Inhibidores de Serina Proteinasa/administración & dosificación , Inhibidores de Serina Proteinasa/farmacología , Uniones Estrechas/efectos de los fármacos , TriptasasRESUMEN
Tween 80 (Polysorbate 80) is a hydrophilic nonionic surfactant commonly used as an ingredient in dosing vehicles for pre-clinical in vivo studies (e.g., pharmacokinetic studies, etc.). Tween 80 increased apical to basolateral permeability of digoxin in Caco-2 cells suggesting that Tween 80 is an in vitro inhibitor of P-gp. The overall objective of the present study was to investigate whether an inhibition of P-gp by Tween 80 can potentially influence in vivo absorption of P-gp substrates by evaluating the effect of Tween 80 on the disposition of digoxin (a model P-gp substrate with minimum metabolism) after oral administration in rats. Rats were dosed orally with digoxin (0.2 mg/kg) formulated in ethanol (40%, v/v) and saline mixture with and without Tween 80 (1 or 10%, v/v). Digoxin oral AUC increased 30 and 61% when dosed in 1% and 10% Tween 80, respectively, compared to control (P < 0.05). To further examine whether the increase in digoxin AUC after oral administration of Tween 80 is due, in part, to a systemic inhibition of digoxin excretion in addition to an inhibition of P-gp in the GI tract, a separate group of rats received digoxin intravenously (0.2 mg/kg) and Tween 80 (10% v/v) orally. No significant changes in digoxin IV AUC was noted when Tween 80 was administered orally. In conclusion, Tween 80 significantly increased digoxin AUC and Cmax after oral administration, and the increased AUC is likely to be due to an inhibition of P-gp in the gut (i.e., improved absorption). Therefore, Tween 80 is likely to improve systemic exposure of P-gp substrates after oral administration. Comparing AUC after oral administration with and without Tween 80 may be a viable strategy in evaluating whether oral absorption of P-gp substrates is potentially limited by P-gp in the gut.
Asunto(s)
Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/metabolismo , Digoxina/farmacocinética , Absorción Intestinal/efectos de los fármacos , Absorción Intestinal/fisiología , Polisorbatos/química , Polisorbatos/farmacocinética , Tensoactivos/química , Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/antagonistas & inhibidores , Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/efectos de los fármacos , Administración Oral , Animales , Área Bajo la Curva , Cromatografía Liquida/métodos , Digoxina/administración & dosificación , Digoxina/sangre , Evaluación Preclínica de Medicamentos/métodos , Quimioterapia Combinada , Predicción , Semivida , Inyecciones Intravenosas , Intubación Gastrointestinal , Masculino , Espectrometría de Masas/métodos , Preparaciones Farmacéuticas , Vehículos Farmacéuticos/administración & dosificación , Vehículos Farmacéuticos/química , Vehículos Farmacéuticos/farmacocinética , Polisorbatos/administración & dosificación , Ratas , Ratas Sprague-Dawley , Tensoactivos/administración & dosificación , Tensoactivos/farmacocinéticaRESUMEN
Digoxin is a cardiac glycoside that is widely used for the treatment of congestive heart failure. To evaluate pharmacokinetics of digoxin in rats, a sensitive LC/MS/MS assay was developed and validated for the determination of digoxin concentration in rat plasma. For detection, a Sciex API3000 LC/MS/MS with atmospheric pressure ionization (API) mass spectrometry turbo ion spray inlet in the positive ion-multiple reaction monitoring mode was used to monitor precursor-->product ions of m/z 798.6-->651.6 for digoxin and m/z 577.6-->433.3 for oleandrin, the internal standard (IS). The standard curve was linear (r(2)>or=0.999) over the digoxin concentration range of 0.1-100 ng/ml in plasma for digoxin. The mean predicted concentrations of the quality control samples deviated by <5.8% from the corresponding nominal values; the intra-assay and inter-assay precision of the assay were within 8.6% relative standard deviation. At the lower limit of quantitation (LLQ) of 0.1 ng/ml, the mean deviation of predicted concentrations from the nominal value was within 3.7%. The extraction recoveries of digoxin and internal standard were 82.7+/-3.9 and 105.9+/-2.3%, respectively. The present method was successfully applied to characterization of pharmacokinetic profiles of digoxin in rats after oral administration.
Asunto(s)
Cardiotónicos/sangre , Cromatografía Líquida de Alta Presión/métodos , Digoxina/sangre , Espectrometría de Masas/métodos , Administración Oral , Animales , Cardiotónicos/administración & dosificación , Cardiotónicos/farmacocinética , Digoxina/administración & dosificación , Digoxina/farmacocinética , Masculino , Ratas , Ratas Sprague-Dawley , Estándares de Referencia , Reproducibilidad de los Resultados , Sensibilidad y EspecificidadRESUMEN
We have previously disclosed the selective ET(A) receptor antagonist N-(3,4-dimethyl-5-isoxazolyl)-4'-(2-oxazolyl)[1,1'-biphenyl]-2-sulfonamide (1, BMS-193884) as a clinical development candidate. Additional SAR studies at the 2'-position of 1 led to the identification of several analogues with improved binding affinity as well as selectivity for the ET(A) receptor. Following the discovery that a 3-amino-isoxazole group displays significantly improved metabolic stability in comparison to its 5-regioisomer, the 3-amino-isoxazole group was combined with the optimal 2'-substituent leading to 16a (BMS-207940). Compound 16a is an extremely potent (ET(A) K(i) = 10 pM) and selective (80,000-fold for ET(A) vs ET(B)) antagonist. It is also 150-fold more potent and >6-fold more selective than 1. The bioavailability of 16a was 100% in rats and the systemic clearance and volume of distribution are higher than that of 1. In rats, intravenous 16a blocks big ET pressor responses with 30-fold greater potency than 1. After oral dosing at 3 micromol/kg, 16a displays enhanced duration relative to 1.
Asunto(s)
Antagonistas de los Receptores de Endotelina , Oxazoles/síntesis química , Sulfonamidas/síntesis química , Administración Oral , Animales , Presión Sanguínea/efectos de los fármacos , Células CHO , Células CACO-2 , Arterias Carótidas/efectos de los fármacos , Arterias Carótidas/fisiología , Cricetinae , Humanos , Técnicas In Vitro , Isoxazoles/síntesis química , Isoxazoles/farmacocinética , Isoxazoles/farmacología , Macaca fascicularis , Masculino , Contracción Muscular/efectos de los fármacos , Oxazoles/farmacocinética , Oxazoles/farmacología , Conejos , Ratas , Ratas Sprague-Dawley , Receptor de Endotelina A , Receptor de Endotelina B , Relación Estructura-Actividad , Sulfonamidas/farmacocinética , Sulfonamidas/farmacologíaRESUMEN
The ET(A) receptor antagonist (2) (N-(3,4-dimethyl-5-isoxazolyl)-4'-(2-oxazolyl)-[1,1'-biphenyl]-2-sulfonamide, BMS-193884) shares the same biphenyl core as a large number of AT(1) receptor antagonists, including irbesartan (3). Thus, it was hypothesized that merging the structural elements of 2 with those of the biphenyl AT(1) antagonists (e.g., irbesartan) would yield a compound with dual activity for both receptors. This strategy led to the design, synthesis, and discovery of (15) (4'-[(2-butyl-4-oxo-1,3-diazaspiro[4.4]non-1-en-3-yl)methyl]-N-(3,4-dimethyl-5-isoxazolyl)-2'-[(3,3-dimethyl-2-oxo-1-pyrrolidinyl)methyl]-[1,1'-biphenyl]-2-sulfonamide, BMS-248360) as a potent and orally active dual antagonist of both AT(1) and ET(A) receptors. Compound 15 represents a new approach to treating hypertension.